The present invention relates to a biochip reader for detecting a binding spot on a biochip having an array of spots that bind with specific biological substances, and to a labeling reagent desirable for producing the biochip to be read with such a biochip reader.
Conventionally, in order to identify and/or fractionate biological molecules, particularly to detect DNA of interest or detect the presence of gene DNA, method of hybridization is often employed where probes such as nucleic acids or proteins having known sequences are used to hybridize to a sample nucleic acid or a sample protein. A biochip is provided with spots of probes (e.g., nucleic acids, proteins, etc.) integrated thereon at a high density, and is used to efficiently detect DNA of interest or detect the presence of gene DNA.
FIG. 6 is a schematic view showing an exemplary structure of a conventional biochip reader. Currently, a fluorescence reading technique is generally employed as a technique for detecting the hybridized spots. The sample nucleic acid or the sample protein is labeled with a fluorescent substance, and then subjected to hybridization to the probes spotted on the biochip. An excitation beam 16 from a laser 15 as an excitation light source is reflected off a dichroic mirror 17 and passed through a condenser lens 18 to radiate the spots hybridized with the sample. The fluorescent substance which labels the sample is excited by this excitation light. The emitted fluorescence is converged by the condenser lens 18, passes through the dichroic mirror 17 and an optical interference filter 19 which selectively transmits the fluorescence component to cut optical components causing noise, and is guided to a photomultiplier 20. The photomultiplier 20 is a point sensor, so a controller 4 make the photomultiplier 20 to scan the sample in X- and Y-directions and a computer 5 acquires the scanned data as an image from the photomultiplier 20.
According to such a conventional fluorescence technique, however, an expensive laser 15 and an expensive optical system are required for the reading process, thereby increasing the cost of the device. Furthermore, the fluorescence intensity from the fluorescent substance is weak, and the wavelength of the fluorescence is not sufficiently far from that of the excitation light to completely remove the excitation light with the optical interference filter 19 in front of the photomultiplier 20. As a result, detection with the fluorescence label does not give highly-sensitive detection.
In view of the above-described problem, the present invention has an objective of providing a biochip reader which is more sensitive and inexpensive than- the fluorescence technique, and providing a labeling reagent desirable for producing a biochip that is read by such a biochip reader.
A biochip reader of the present invention comprises: a magnetic sensor for reading the strength of the magnetic field on a plane; and a scanning unit for driving the magnetic sensor and the biochip so that the magnetic sensor scans the biochip relatively in a two-dimensional manner.
The scanning unit rotates the biochip and drives the magnetic sensor in a uniaxial direction perpendicular to the rotating direction, thereby incorporating a disk-reading mechanism of a general hard disk drive.
Furthermore, a labeling reagent of the present invention comprises a ferromagnetic substance for labeling a biological substance.